In certain machines, such as vertical, numerical control machines, wherein a head mounting a main tool drive spindle is supported by a pair of machine ways for vertically directed reciprocating movements relative to a workpiece suoporting table, it is common practice to provide an essentially continuous supply of oil to the machine ways for lubrication purposes and of dissimilar coolant fluid to the workpiece in order to remove heat generated during a machining operation. A problem heretofore encountered with machines of this general tyoe is that lubricating oil flowing downwardly along the machine ways continuously drips into the coolant collection reservoir and contaminates the coolant. As the degree of contamination increases, a point is reached after which the coolant can no longer be satisfactorily used in connection with the machining operation and thus it must be drained from the machine and replaced with fresh or new coolant. Aside from environmental considerations connected with the disposal of contaminated coolant, the required periodic replacement of coolant greatly increases the cost of machine operation, due both to the relatively high cost of coolant material and the operator/machine time lost during the coolant draining/replacement operation.
An additional problem resulting from lubricating oil contamination of coolant is that an oil film is built up on surfaces of the machine contacted by the contaminant coolant with the result that chips and other debris created during a machining operation tend to stick or adhere to such oil film and greatly increase the degree of difficulty and time involved in cleaning such debris from the machine.
Devices in the form of shields have been employed to prevent splashing of coolant onto the machine ways in order to prevent its interference with the proper lubrication thereof, but such devices are ineffective in preventing lubricating oil contamination of the coolant.